High blood pressure can occur in pregnancy in two forms. It may be a preexisting condition, called chronic hypertension, or it can develop during pregnancy--a condition known as gestational hypertension. It is also called toxemia or preeclampsia and occurs most often in young women with a first pregnancy.
AC relays. AC relays are manufactured similar to their DC counterparts. If AC current is applied to a DC relay, the relay will pulse at the frequency of the AC current. To overcome this problem, the core is equipped with a shading ring on one-half of the core (Photo 2).
A mechanical relay does this through the use of an electromagnet-a magnet that is only on when there's power running through it-that pulls a set of spring loaded contacts to make or break the connection and achieve the on-off effect.t's a electrical device that functions something like a wired remote control switch. Instead of having the switch you push/flip/whatever do the work of supplying power to whatever you wanted it to, you have it control a relay which then does the real on/off switching work. That's it.